Doozandeh Tamim, Jindal Prakhar, Botchu Jyoti
Space System Engineering, Faculty of Aerospace Engineering, Delft University of Technology, 2629 HS Delft, The Netherlands.
Materials (Basel). 2025 Jul 7;18(13):3196. doi: 10.3390/ma18133196.
This study presents a comprehensive finite element investigation into the design optimization of an ultra-high temperature ceramic matrix composite thruster for green bipropellant systems. Focusing on ZrB-SiC-Cfiber composites, it explores their thermal and mechanical response under realistic transient combustion conditions. Two geometries, a simplified and a complex full-featured model, were evaluated to assess the impact of geometric fidelity on stress prediction. The complex thruster model (CTM) offered improved resolution of temperature gradients and stress concentrations, especially near flange and convergent regions, and was adopted for optimization. A parametric study with nine wall thickness profiles identified a 2 mm tapered configuration in both convergent and divergent sections that minimized mass while maintaining structural integrity. This optimized profile reduced peak thermal stress and overall mass without compromising safety margins. Transient thermal and strain analyses showed that thermal stress dominates initially (≤3 s), while thermal strain becomes critical later due to stiffness degradation. Damage risk was evaluated using temperature-dependent stress margins at four critical locations. Time-dependent failure maps revealed throat degradation for short burns and flange cracking for longer durations. All analyses were conducted under hot-fire conditions without cooling. The validated methodology supports durable, lightweight nozzle designs for future green propulsion missions.
本研究对用于绿色双组元推进剂系统的超高温陶瓷基复合材料推进器的设计优化进行了全面的有限元研究。以ZrB-SiC-C纤维复合材料为重点，探讨了它们在实际瞬态燃烧条件下的热响应和力学响应。评估了两种几何形状，即简化模型和复杂的全功能模型，以评估几何逼真度对应力预测的影响。复杂推进器模型（CTM）能更好地解析温度梯度和应力集中情况，尤其是在法兰和收敛区域附近，因此被用于优化。一项针对九种壁厚剖面的参数研究确定，在收敛段和发散段均采用2毫米的锥形配置可在保持结构完整性的同时使质量最小化。这种优化后的剖面降低了峰值热应力和整体质量，同时不影响安全裕度。瞬态热分析和应变分析表明，热应力在初始阶段（≤3秒）起主导作用，而由于刚度退化，热应变在后期变得至关重要。使用四个关键位置处与温度相关的应力裕度评估了损伤风险。随时间变化的失效图显示，短时间燃烧会导致喉部退化，长时间燃烧会导致法兰开裂。所有分析均在无冷却的热火条件下进行。经过验证的方法学为未来绿色推进任务支持耐用、轻质的喷嘴设计。
